Ever since Buzz Aldrin and Neil Armstrong gave former Dutch prime minister William Drees a chunk of moon-rock in 1969, the public has been eager to see it. In fact, the relic has drawn tens of thousands of people to Amsterdam’s Rijksmuseum.

But Houston, we have a problem: Turns out that so-called moon rock (which was insured for 308,000 British pounds, or about $500,000) is really just a hunk of petrified wood—and its actual value is less than 50 British pounds.

Researchers Amsterdam’s Free University were able to tell at a glance that the rock was unlikely to be from the moon, a conclusion that was borne out by tests. “It’s a nondescript, pretty-much-worthless stone,” said Frank Beunk, a geologist involved in the investigation [of the rock].

Xandra van Gelder, who oversaw the investigation, said the museum would continue to keep the stone as a curiosity. “It’s a good story, with some questions that are still unanswered,” she said. “We can laugh about it.”

An investigation is under way to find out how the heck this debacle could have happened (a bait-and-switch, perhaps?). Meanwhile, we bet moon conspiracists will view this discovery as far from a laughing matter—in fact, it may add fuel to their argument that the moon landing never really happened. (For the record, it did.)

In 2004, geologist Phil Christensen flew from Arizona to Ireland to collect volcanic rocks for research on how rocks formed on Mars. While there, he noticed a school nearby and thought it would be brilliant if kids could just collect the rocks and mail them to him.

After the trip, he briefly worked on NASA’s Mars missions and announced at one of their press conferences that he’d welcome packages of rocks from anywhere around the world.

News traveled fast (and this is even before the days of Twitter): The first rock arrived at his home base at Arizona State University in Tempe three days after the request. Two weeks later, 150 rocks came in the mail. Now, five years later, he has received more than ten thousand rocks from children in 80 countries. A full list of the rock types mailed in can be seen here.

Each rock has been catalogued, and most have been studied to determine their composition. Every person who sends in a rock gets a certificate, with the rock’s number, signed by Christensen. The Rock Around the World Web site has directions for people who want to send in their prized chunk of earth.